The present invention relates to a method for the dehydrogenation of triisopropyl benzene (hereinafter referred to as TIPB) and diisopropyl benzene.
Particularly, the present invention relates to a method for the dehydrogenation of TIPB in a vapor phase at an elevated temperature in the presence of steam to produce diisopropyl isopropenyl benzene (hereinafter referred to as DIPIPeB), isopropyl diisopropenyl benzene (hereinafter referred to as IPDIPeB) and/or triisopropenyl benzene (hereinafter referred to as TIPeB), and also to a method for the dehydrogenation of diisopropyl benzene in a vapor phase at an elevated temperature in the presence of steam to produce isopropenyl cumene and diisopropenyl benzene.
DIPIPeB, IPDIPeB, TIPeB, isopropenyl cumene, and diisopropenyl benzene are important compounds as intermediates in organic synthesis or as monomer components of functional polymers.
Until now, processes for the dehydrogenation of aromatic hydrocarbons to produce dehydrogenated aromatic hydrocarbons have been described in many publications in the past. For example, processes for the dehydrogenation of ethylbenzene to produce styrene are industrially carried out employing iron-based catalysts.
However, there is not known any method for the dehydrogenation of TIPB to economically produce DIPIPeB, IPDIPeB and/or TIPeB.
On the other hand, with respect to catalysts for dehydrogenating diisopropyl benzene, many proposals have been put forward until now. For example, there are known copper-chromium catalysts (CA, 14, 7383h), iron-chromium-potassium catalysts (Nissan Gardler Co.,Ltd. G64) (U.S. Pat. No. 3,429,941), iron-chromium-potassium-magnesium catalysts (CA, 81, 169877z), melt lithium or lead iodide catalysts (CA, 86, 55085n), and the like.
In addition, methods for purifying diisopropenyl benzene are also known (Japanese Patent Laid-Open No. 65029/1984 and Japanese Patent Laid-Open No. 204733/1985), but dehydrogenating catalysts and detailed reaction conditions are not described.
Catalysts thus far known cannot be yet satisfactory for industrial operation due to problems of the activity and catalyst life, and additionally have problems of requiring enormous costs of disposition as spent catalysts in view of environmental matter, since all the catalysts except for melt lithium or lead iodide catalysts contain chromium. Therefore, it is difficult to say that these catalysts are good industrial catalysts. Furthermore, in the case where melt lithium or lead iodide catalysts are employed, there are problems in methods of handling the catalysts in a melting state.
With respect to these reaction conditions, in the case of the production of styrene as a typical example of dehydrogenation reactions, the reaction is performed diluting with steam, on equilibrium grounds and for the purpose of removing carbonous material on the catalyst. The amount of steam is supplied at a weight ratio in the order of 1, relative to ethylbenzene as the raw material. With respect to the catalyst life, it is presumed that the catalyst is exchanged upon carrying out the regular maintenance once a year, but it seems that this cannot lead to industrialization at all, from information to date on the catalyst life in the reaction of dehydrogenating diisopropyl benzene or triisopropyl benzene.
Thus, in the case where problems exist in the catalyst life, there are required an increase in catalyst costs and disposition of spent catalysts resulting from catalyst exchange, or the shutdown of the operation or the opening of the reactor due to catalyst exchanging work, or the like, and therefore processes will become economically disadvantageous.
Subjects of the present invention are to provide an economical and industrial method for the dehydrogenation of TIPB and diisopropyl benzene and furthermore a continuously and stably operating method in which an environment-friendly catalyst not containing chromium as a catalyst component is employed and the deterioration of the catalyst is avoided.
The inventors have carried out intensive researches to solve problems described above, and obtained the finding that in the dehydrogenation of TIPB as the raw material, a reaction carried out employing a solid catalyst having an iron compound and potassium compound as major components or a solid catalyst having an iron compound, potassium compound, and magnesium compound as major components gives intended products DIPIPeB, IPDIPeB and/or TIPeB in a high yield and at a high selectivity, IA which has led to the completion of the present invention.
The inventors have also found that in the presence of a solid catalyst having an iron compound and potassium compound as major components or a solid catalyst having an iron compound, potassium compound, and magnesium compound as major components, a reaction in which a catalyst regeneration period with steam or oxygen or air is provided and the raw material diisopropyl benzene or triisopropyl benzene is fed intermittently can be carried out to obtain its intended products, namely, isopropenyl cumene and diisopropenyl benzene, or diisopropyl isopropenyl benzene, isopropyl diisopropenyl benzene and/or triisopropenyl benzene, in a high yield, with an improved life of the catalyst and at the same time a selectivity retained at a high level, which has led to the completion of the present invention.
In short, in a method for the dehydrogenation of TIPB in a vapor phase at an elevated temperature in the presence of steam and a solid catalyst to produce DIPIPeB, IPDIPeB and/or TIPeB, the present invention consists in a method for the dehydrogenation of TIPB in which the solid catalyst has an iron compound and potassium compound as major components. The present invention also consists in a method for the dehydrogenation of TIPB in which the solid catalyst has an iron compound, a potassium compound and a magnesium compound as major components.
Also, the present invention consists in a method for the dehydrogenation of triisopropyl benzene in a vapor phase at an elevated temperature in the presence of steam and a solid catalyst to produce diisopropyl isopropenyl benzene, isopropyl diisopropenyl benzene and/or triisopropenyl benzene, wherein:
i) the solid catalyst has an iron compound and a potassium compound as major components, or the solid catalyst has an iron compound, a potassium compound and a magnesium compound as major components, and
ii) a combination of a reaction period and a catalyst regeneration period is made by feeding triisopropyl benzene intermittently.
In the reaction period, two components of the triisopropyl benzene and the steam contact with the solid catalyst, and in the catalyst regeneration period, only the steam contacts with the solid catalyst.
Further, the present invention consists in a method for the dehydrogenation of diisopropyl benzene in a vapor phase at an elevated temperature in the presence of steam and a solid catalyst to produce isopropenyl cumene and diisopropenyl benzene, wherein:
i) the solid catalyst has an iron compound and a potassium compound as major components, or the solid catalyst has an iron compound, a potassium compound, and a magnesium compound as major components, and
ii) a combination of a reaction period and a catalyst regeneration period is made by feeding diisopropyl benzene intermittently.
In the reaction period, two components of the diisopropyl benzene and the steam contact with the solid catalyst, and in the catalyst regeneration period, only the steam contacts with the solid catalyst.